Manufacture of articles from fibrous material



Nov. 7, 1961 c. H. MAYNE 3,007,842

MANUFACTURE OF ARTICLES FROM FIBROUS MATERIAL Filed Aug. 18, 1958 IN VINTOR.

CHARLES HENRY MAYNE BvwW United States Patent ()fiice 3,007,842 PatentedNov. 7, 1961 3,007,842 MANUFACTURE OF ARTICLES FROM FIBROUS MATERIALCharles Henry Mayne, Woodford Green, Essex, England,

assignor to Hawley Products Company, St. Charles,

111., a corporation of Delaware Filed Aug. 18, 1958, Ser. No. 755,701 3Claims. (Cl. 162-429) This invention relates to the manufacture ofarticles from fibrous material and is more particularly, but notexclusively concerned with the production of acoustic diaphragms. It iswell known to manufacture articles from fibrous material by producing anaccretion of the material onto a suitably shaped mould immersed in abath of an aqueous slurry of the fibrous material. Briefly speaking,known methods involve strongly agitating a bath of the slurry by forcingcompressed air into the slurry so that the fibrous material is welldistributed throughout the bath and so that the material is preventedfrom settling out of the water in the bath, and sucking the slurrytowards the mould thereby to form a layer of fibrous material on themould. After the desired thickness of the layer has been achieved, themould, plus the layer, is raised above the surface of the bath, and thelayer is removed from the mould for further treatment.

As will be appreciated, considerable quantities of air must be used inorder to maintain the desired uniformity of suspension. The provision oflarge quantities of pressurized air necessarily involves considerablebulk and costs in the actual molding equipment, and also auxiliaryequipment such as compressors.

According to the present invention, there is provided a method ofagitating a bath of fluid mixed with a fibrous material by reciprocatingat least a part of the fluid through a restriction.

According to a second aspect of the invention, there is provided amethod of forming an article from fibrous material comprising the stepof reciprocating a quantity of a slurry containing the fibrous materialthrough a venturi.

In a preferred form of apparatus, an aqueous slurry containing fibrousmaterial is provided in a conical container having a flexible diaphragmas its base and a venturi at the top of the container, there being meansfor reciprocating the base to agitate and force the slurry through theventuri, a mould located above and adjacent the venturi and a vacuumsystem for sucking slurry towards the mould.

For a better understanding of the invention, reference will now be madeto the accompanying drawing which is a sectional schematic view of themoulding apparatus.

In the drawing, 1 is a conically shaped container having a cylindricalneck-part 1a and a base 2 which is constituted by a flexible diaphragm.The diaphragm is connected to the container 1 by being clamped between aflange 1b on the container and an annular clamping ring 10. A venturi 3is provided in the neck 1a, one part 3a of the venturi forming acontinuation of the sloping wall of the container, whilst the other part3b of the venturi 3 opens outwardly to connect with the cylindrical neckpart 1a.

A mechanism generally indicated at 4, is provided beneath the diaphragm2 for reciprocating the diaphragm 2 in a vertical direction. Themechanism 4 is schematically represented by a connecting piece 4a whichis coupled with the diaphragm. The piece 4a is supported by uprights 4bcarried on a cross-member 4c, the latter being slidably carried onpillars 4d.

An elongated slot 4e is formed in the cross-member 4c, the slot 42,being engaged by a pin 4] provided on a wheel 4g carried on a shaft 4h.The pin 4 is eccentric with respect to the shaft 4h; consequently,rotation of the wheel 4g will cause the cross-member 4c to reciprocatein a vertical direction. The reciprocatory movement of the cross-member40 will reciprocate the diaphragm 2.

Immediately above the venturi 3 there is a felting form mould 7 which issuitably supported within the neck 1a. The interior of the mould isconnected with a vacuum system in such manner that suction can beapplied to the interior of the mould. The vacuum system includes avacuum release valve 8, a vacuum line 9, a vacuum header tank 10 and aconnection 11 to a vacuum (not shown).

The fibrous material in suspension is fed to the container 1 via a pipe5. A suitable valve 5a is provided in the pipe 5. The container 1 isfilled with a mixture of water and fibrous material to form a slurrywhich, when the diaphragm is in the position shown by the full linesreaches the height A in the cylindrical neck 1a.

A pipe 6, including a suitable valve means 6A, is connected to thecontainer to enable the introduction of water into the container. Theapparatus is used as follows:

The correct mixture of water and fibrous material is introduced into thecontainer. The vacuum system is switched on and the wheel 4g is rotatedat a predetermined rate of rotation. As the wheel 4g rotates, thediaphragm 2 is reciprocated between the full line position, and thedotted line position shown in the drawing. These positions are calledthe first stage and second stage positions. When the diaphragm is in thesecond stage position the surface level of the slurry falls to level B.It is found that the movement of the diaphragm in conjunction with theventuri causes the fibrous material to form the desired suspension.

A moulding cycle can be considered as commencing when the diaphragm ismoved from the second stage to the first stage. Such movement of thediaphragm causes the slurry to move through the venturi 3 and moves thesurface of the liquid from B to A. This movement shuts off the vacuumrelease valve 8, completely immerses the mould 7 (or felting form) andproduces the desired fibrous material suspension. The time cycle ofdiaphragm reciprocation is such that material sufficient to form thearticle has been drawn onto the mould by the vacuum system by the timethe liquid level has returned from A to B. The vacuum system draws off aquantity of liquid and fibre during each cycle. The requisitereplacement quantities of fibrous material and fluid are added to thebath via pipes 5 and 6.

It will be clear that the above apparatus eliminates the need forcompressed air to agitate the bath. That is, aeration of the pulp isavoided. The fluid used in the apparatus need not be aqueous since itcan be used with non-aqueous materials.

The range of articles which can be moulded in the apparatus may coverweights ranging from a few grains to several pounds. The articles may bemade of a wide range of fibrous material organic and inorganic, naturaland synthetic together with the incorporation of various binding mediasuch as resin and resins, natural and synthetic latices.

It is clear that the above described method and apparatus is applicableto the maintenance of a suspension of a material other than fibrousmaterial in. a fluid.

What I claim is:

1. A method of forming an article from a fibrous material whichcomprises: reciprocating a slurry of said material within a containerwherein during the first cycle of the reciprocation of the slurry thesurface of the liquid is moved from a first position beneath a formingmould to a second position above the mould, wherein during the secondcycle of said reciprocation the surface of liquid is moved from thesecond position to said first position beneath said mould, wherein saidliquid passes through a venturi in moving from said first position tosaid second position and in moving from said second position back tosaid first position, and wherein the movement of the surface of theliquid between the two positions actuates a vacuum system whereby saidfibrous material is drawn toward said mould.

2. A method as in claim 1 wherein the movement of the surface of theliquid from the first position to the second position actuates a vacuumsystem which draws the fibrous material toward said mould, and whereinthe cycle of reciprocation is such that material sufficient to form thearticle to be moulded is drawn onto the mould by the time the liquidlevel has returned to said first position.

3. Apparatus for forming an article from a slurry of fibrous materialwhich comprises a conically shaped container having a flexible diaphragmas its base and having a venturi adjacent to its apex, means forreciprocating said base to move said slurry within said container in areciprocating motion through said venturi, a mould within said containerand above said venturi, and a vacuum system for sucking the slurrytoward said mould whereby fibrous material within the slurry isdeposited onto said mould.

References Cited in the file of this patent UNITED STATES PATENTS1,203,197 Hogue Oct. 31, 1916 1,673,047 Hawley June 12, 1928 2,196,193Chambers et a1. Apr. 9, 1940 2,234,979 Randall et a1 Mar. 18, 19412,498,737 Holden Feb. 28, 1950 2,916,265 Towne Dec. 8, 1959

1. A METHOD OF FORMING AN ARTICLE FROM A FIBROUS MATERIAL WHICHCOMPRISES: RECIPROCATING A SLURRY OF SAID MATERIAL WITHIN A CONTAINERWHEREIN DURING THE FIRST CYCLE OF THE RECIPROCATION OF THE SLURRY THESURFACE OF THE LIQUID IS MOVED FROM A FIRST POSITION BENEATH A FORMINGMOULD TO A SECOND POSITION ABOVE THE MOULD, WHEREIN DURING THE SECONDCYCLE OF SAID RECIPROCATION THE SURFACE OF LIQUID IS MOVED FROM THESECOND POSITION TO SAID FIRST POSITION BENEATH SAID MOULD, WHEREIN SAIDLIQUID PASSES THROUGH A VENTURI IN MOVING FROM SAID FIRST POSITION TOSAID SECOND POSITION AND IN MOVING FROM SAID SECOND POSITION BACK TOSAID FIRST POSITION, AND WHEREIN THE MOVEMENT OF THE SURFACE OF THELIQUID BETWEEN THE TWO POSITIONS ACTUATES A VACUUM SYSTEM WHEREBY SAIDFIBROUS MATERIAL IS DRAWN TOWARD SAID MOULD.